1. Field of the Invention
The present invention relates to a humidification unit, a humidifying unit for an artificial respiratory device, and a method for manufacturing of a humidification unit.
2. Description of the Related Art
Japanese Patent Application Unexamined Publication No. 62-26, 076 discloses a humidification unit that uses a gas permeable tube having a peripheral wall with minute openings defined in the wall. The openings are large enough to allow water vapor to permeate through the peripheral wall yet small enough to prevent water from passing therethrough. More specifically, this humidification unit includes a gas permeable tube having a peripheral wall with minute openings that are arranged in such a way that an electrically exothermic member having an inner diameter of at least 3 mm or larger is disposed in this single gas permeable tube. During use, the gas permeable tube communicates with a water supply source and is filled in with water. Water vapors are discharged from the gas permeable tube through the minute openings provided in the peripheral wall with the aid of heat generated from the electrically exothermic member.
The humidification unit described above, however, has a disadvantage in that should the gas permeable tube break, an unacceptably large amount of water is likely to leak outside the tube. For example, in the case where such a humidification unit is employed in a patient circuit for an artificial respiratory device, a large quantity of leaking water from the gas permeable tube may become hazardous, especially if the leaked water causes a decrease in the humidifying function or if the leaked water flows into the intake side of the artificial respiratory device, i.e., the side connected to a patient.
Accordingly, it is on object of the present invention to provide a humidification unit that does not suffer from the shortcomings of the above-described conventional humidification devices. It is a further object to provide a humidification unit that is capable of minimizing leakage from the humidification unit should the unit be damaged while still sustaining the humidifying function.
The present invention has a another object to provide an artificial respiratory system using such a humidification unit.
Further, the present invention has an object to provide a method for manufacturing such a humidification unit.
In order to achieve these objects, the present invention provides a humidification unit comprising an exothermic member having an outer surface and a plurality of hollow fibers disposed on the outer surface of the exothermic member. Each hollow fiber has a peripheral wall with minute openings that are large enough to allow a gas, such as water vapor, to permeate therethrough, yet small enough to prevent a liquid, such as water, from passing therethrough.
Furthermore, in order to achieve the above objects, the present invention provides a humidification unit comprising an exothermic member having an outer surface and a plurality of hollow fibers disposed on the outer surface of the exothermic member. Each hollow fiber has peripheral wall with minute openings that are large enough to allow a gas, such as water vapor, to permeate therethrough, yet small enough to prevent a liquid, such as water, from passing therethrough. The exothermic member and hollow fibers define a humidification element, which is coupled to a short connection tube that is adapted to be detachably connected to a patient circuit in an artificial respiratory system. Providing a support member in the form of the connection tube to which the humidification element is attached, allows the entire assemble to be readily disposed into the patient circuit.
In order to achieve the other objects as described herein above, the present invention provides an artificially respiratory system and method of using same that includes a pressure generator adapted to generate a flow of breathing gas, a patient circuit coupled to the pressure generator for delivering the flow of breathing gas to the patient, and a humidification unit disposed in the patient circuit. The humidification unit comprises an exothermic member having an outer surface and a plurality of hollow fibers disposed on the outer surface of the exothermic member. Each hollow fiber has peripheral wall with minute openings that are large enough to allow a gas, such as water vapor, to permeate therethrough, yet small enough to prevent a liquid, such as water, from passing therethrough. In a further embodiment, a fluid supply source communicates with the multiple hollow fibers to supply liquid thereto.
The above objects are also achieved by providing a method for preparing a humidification unit that includes the steps of providing a plurality of hollow fibers, wherein each hollow fiber is defined by a peripheral wall having minute openings large enough to allow a gas to pass therethrough, yet small enough to prevent a liquid from passing therethrough, and winding the hollow fibers around an exothermic member such that the plurality of hollow fibers are disposed on the outer surface of the exothermic member. In a further embodiment, the plurality of hollow fibers are arranged in a sheet, and the sheet of hollow fibers are wound around the exothermic member such that a longitudinal axis of the plurality of hollow fibers is substantially parallel to a longitudinal axis of the exothermic member. In a still further embodiment, the plurality of hollow fibers are arranged in a strip, and the strip of hollow fibers are wound around the exothermic member in spiral fashion.
Because the plurality of hollow fibers disposed on the outer surface of the exothermic member define a humidification element with a relatively small diameter and because each hollow fiber has a peripheral wall with minute openings that are large enough to allow a gas to permeate therethrough, yet small enough to prevent a liquid from passing therethrough, the humidification element can be disposed in a path having a small diameter, and can still provide a significant humidifying function by heating the multiple hollow fibers with the exothermic member. Furthermore, even if a few of the hollow fibers are damaged, broken, etc., the humidifying function is not significantly compromised, and water leaking from the humidification element is minimized. In addition, the exothermic member supports the multiple hollow fibers so that the entire unit can be transported and handled relatively easily.
By providing an exothermic member that consists of an electrically controlled exothermic member, the amount of heat to be applied to the water in the multiple hollow fibers can be controlled, without waste and with a high degree of precision. Accordingly, the humidification unit according to the present invention can ensure reliability and stability in its humidifying function.
By providing an exothermic member consisting of a heating wire for generating heat upon transmission of electric current thereto, and by providing an electrically insulating member disposed around the heating wire for ensuring electrical insulation, the humidification unit can ensure safety upon use, because the insulating performance can be ensured even if an electrically powered exothermic member is employed as the exothermic member.
On the other hand, by providing a heat pipe as the exothermic member, the structure of the humidification unit can be simplified, because it does not require electrical insulation. Such a heat pipe also provides support for the multiple hollow fibers held on the heat pipe employed as the exothermic member.
Winding the multiple hollow fibers around the exothermic member improves the transmission of heat from the exothermic member to the multiple hollow fibers. In addition, the humidifying ability can be readily increased or decreased by adjusting the amount of the multiple hollow fibers wound around the exothermic member.
In a further embodiment of the present invention, the ends the multiple hollow fibers are joined together and a connector is provided for connecting the fibers to a fluid source. In a still further embodiment, the connector to the supply of fluid is located on only one end of the fibers, thereby simplifying the use of the humidification unit so that only one fluid connection is required. In another embodiment, however, both ends of the multiple hollow fibers are connected to the fluid supply source to allow fluid to be supplied to both ends of the multiple hollow fibers so that the supply of fluid to each of the multiple hollow fibers can be performed at a high speed and with high precision. Also, should one supply of fluid fail or become blocked, the other serves as a backup.
If the multiple hollow fibers are joined at one end portion, which is the same as the side of the electric current supply end of the exothermic member, the electric current supply system and the water supply system can be concentrated at one location.